1. Field of the Invention
The present invention relates to an image input apparatus and a fingerprint recognition apparatus for recognizing characters or images of originals, barcodes, fingerprints etc.
2. Related Background Art
Conventionally, as an image input apparatus for recognizing characters or images of originals, barcodes etc., there is an apparatus of a constitution for reading images by moving a hand scanner or the like on an original or the like. This constitution enables the apparatus to be miniaturized and made portable. However, a hand-feeding speed of the hand scanner may be changed to distort images.
Additionally, there is an image input apparatus for authenticating a fingerprint by bringing a finger into direct contact with a two-dimensional semiconductor sensor (electrostatic type, optical reading type or the like) to read a fingerprint. Recently, such a fingerprint sensor has attracted attention in terms of an increase of security for corporations or individuals. Moreover, in E commerce or the like utilizing cell phones or portable devices, great market expansion can be expected if the fingerprint sensor is miniaturized and reduced in weight and cost. In the case of the current fingerprint sensor, however, a sensor size is inevitably increased because the sensor is constituted in size equal to a size of a finger.
Since a price of a semiconductor is uniquely determined by a wafer yield, a large size leads to a high price, and there is a cost problem if it is mounted on the cell phone. Besides, a large fingerprint sensor is not suitable for a compact portable device. Accordingly, it is advantageous in cost and shape if the sensor is miniaturized. As a solution, if the optical reading type is employed and an optical sensor is constituted of a line sensor, the sensor can be miniaturized. In this case, however, since it is necessary to relatively move the line sensor and the finger to read the fingerprint, as in the case of the image reading by the hand scanner, a read fingerprint image is distorted to greatly reduce authentication accuracy.
Thus, there is Japanese Patent No. 3,198,810 as an example of a well-known conventional technique to improve the aforementioned drawback. According to this Patent, a hand feeding speed during character reading of an original is discriminated, and a result of the discrimination is fed back to timing generation means, whereby image distortion is corrected.
The technology disclosed in the Patent No. 3198810 may enable authentication of an image at low resolution if the original or the hand is fed carefully or slowly in original reading. However, the technology cannot be used for the fingerprint sensor or the like which needs high resolution and high authentication accuracy.